A major problem encountered in cutting tow into staple fiber bundles is conveyance of the cut staple in such a manner that subsequent opening required for further processing is not impeded by twist formation or the like. Such twist formation is often observed, especially when cutting long staple fiber. It is generally caused immediately after cutting by turbulence produced by air flow generated by the rotating cutting device. To avoid this phenomenon, attempts have been made to remove cut fiber bundles either by suction or blowing the bundles away from the cutting point. While this occasionally inhibits the formation of twists, there are other shortcomings. When long passages with various changing cross-sections are involved, wadding and lumping resulting in partial obstruction of the lines is usually unavoidable. During the subsequent opening process, this leads in part to serious problems. It has now been found that not only improved conveying of the fiber bundles away from the cutting point of a conventional cutter can be provided, but moreover that opening of the fiber bundle can be combined with such conveying when the suction opening of a specially modified radial blower, with exclusion of leaks, is located as close as possible to the cutting zone of the cutter.
While it has previously been suggested to use a radial blower for conveying the cut staple bundle from the cutting point (See U.S. Pat. No. 2,846,004), in this case not only was the blower located at considerable distance from the cutting point, but guides for the staple bundles exhibited marked changes in cross-sections and/or deflections; an increasing space was not provided between fan blades and housing. The objectives of the present invention could not be met thereby. The devices exhibited not only the described shortcomings, but felting and lumping presented serious difficulties when opening the staple bundles separated from the conveying stream. An additional serious drawback was that the staple was heavily damaged while traveling through the blower.
It was not expected that the combination of two unconventional procedures, (1) aligning the radial blower with its suction opening as close as possible to the cutting point, care being taken that at least the major portion of the intake air flows from one or from combined cutting points, and (2) providing--in distinct contradiction to generally accepted ideas on radial blowers--for an increasing space between fan blades and inside wall of the housing, would be so highly successful in opening and conveying the staple bundles.